“Defining deviancy down,” the late Daniel Patrick Moynihan, an astute social observer, called it.

Draw your own conclusions, therefore, from the news that a journal called Porn Studies has arrived on the scene — accompanied by the inevitable pseudo-scientific blather. Soon to come: The Bestiality Quarterly and The Review of Necrophilia? Just wait and see.

The scientific study of pornography as a symptom of sickness might actually have some value.

But a writer on the Culture of Life website expresses skepticism about Porn Studies since it originates with the same publishing group responsible for a journal of homosexuality that serves largely as an advocate for the gay lifestyle.

Even so, one has to agree with the editors’ rationale that pornography deserves study because it’s important to so many people. What they don’t say is that it coarsens the cultural and moral landscape and blights lives.

With the exception of child pornography — still widely deplored and occasionally punished by law — pornography is now taken for granted in the United States, a kind of background noise you’re supposedly free to ignore if you don’t like it. The Supreme Court used to wrestle with the issue occasionally, but having lowered the legal bars, these days it generally leaves it alone. It’s the price you have to pay for free speech, we’re told.

And after all, pornography does no real harm.

Really? Pope Francis cut to the heart of it in his message for Lent, listing pornography along with addiction to alcohol, drugs and gambling as a form of “moral destitution” whose essence is “slavery to vice and sin.” Often, he noted, it begins with the young.

A central reason for the spread of pornography is that some people get rich from it, thereby capitalizing on the weakness of others. One estimate places the annual value of the U.S. “adult video” trade alone at $20 billion. Pornography is a pervasive presence on the Internet, with an estimated 12 percent of all websites featuring it.

Confessors report that the use of pornography has become a grievous problem for many men. It is a factor in many cases of marriage breakdown, parent-child conflict, and other forms of individual and social pathology.

If all this isn’t real harm, then it’s hard to say what real harm would look like. Yet our courts, acting as agents of a secular cultural elite, have decreed a hands-off approach.

“To a degree that my father could never have imagined, today’s father must protect himself and his children from the relentless assault of an increasingly pornographic culture; moreover, mothers share this sacred task. ...

“Every home now stands in the pathway of this attack on our children’s innocence and purity. If we are not vigilant, our sons and daughters will pay a steep and heartrending price.”

These words come from a pastoral letter, “Bought With a Price,” by Bishop Paul Loverde of Arlington, Va. Its subtitle: “Every Man’s Duty To Protect Himself and His Family from a Pornographic Culture.” Bishop Loverde originally published his letter in 2006. Recently he issued it in an expanded form because the problem has gotten worse.

As the quote makes clear, its message is that the solution is up to everyone, with fathers at the top of the list. No one else will do it for us.